It provides a base class provining all the functionality,
and a descendent classes geneator class.

The main idea is to simplify creation of subclasses
implementing syntax highlighting for particular language.
Subclasses do not implement any new functioanality,
they just provide syntax highlighting rules.
The rules sources are in XML format.

To create a highlighter for a language, there is no need
to code a new class manually. Simply describe the rules
in XML file and use Text_Highlighter_Generator to create
a new class.